so the 'coin man' at a local car boot sale today, had a good selection of those 10p's for sale. i mentioned how i'd never actually seen one 'in the wild' and he said theres a reason for that.
according to him, the first batch in 2018 of 200,000 were never released to banks but to post offices. from there they could and should have made their way into circulation, but, according to coin man, every 'postmaster' in the country, bought the coins themselves (presumably at 10pence each), and flogged them privately to the collectors markets.
he then said the 2019 batch was supposed to be a run of 2 million coins, but so far they haven't all been released.